Removing Texture and Wallpaper?

I am trying to remove foil wallpaper that has been covered by what looks like a plastery substance so the previous owners could paint the walls. It must of been a quick fix to make the walls look good to a potential home buyer. The plaster stuff is thicker in some areas than others so its like an excavation sometimes it is so deep. Is there an easier way to remove the layers and layers? I have used an exacto and spray.